Different ophthalmic artery origins: Embryology and clinical significance

Clinical characteristics of the well-defined upper eyelid vascular network pattern in patients with rosacea

BACKGROUND

Rosacea is a chronic inflammatory skin disease. The diagnosis is based on the symptoms and physical signs, which still lacks objective laboratory tests or imaging tests.

OBJECTIVES

To propose and evaluate the upper eyelid network pattern in rosacea.

METHODS

Participants included patients diagnosed with rosacea, other facial erythematous skin diseases, and normal controls, all of whom underwent full-face imaging utilizing the VISIA® system software. According to these images, researchers evaluated the condition of the upper eyelid vascular network, developed the grading scale and then compared the difference of distribution in the three groups.

RESULTS

The occurrence rate of upper eyelid vascular network in rosacea was significantly higher than that in other facial erythematous skin diseases (84.3 vs. 32.0%, P < 0.001) and normal controls (84.3 vs. 28.0%, P < 0.001). The upper eyelid vascular network pattern was proposed (none [no clearly reticular vessels], mild [10-50% area of reticular vessels], moderate-to-severe [>50% area of reticular vessels]). Moderate-to-severe grade was defined as well-defined upper eyelid vascular network pattern, which was specific to patients with rosacea (rosacea vs. other facial erythematous skin diseases, adjusted odds ratio [aOR] = 5.814, 95% confidence interval [CI]: 3.899-8.670) (rosacea vs. heathy controls, aOR = 12.628, 95% CI: 8.334-19.112). The severity of the well-defined pattern had no significant association with age, duration, and phenotypes of rosacea (P > 0.05).

CONCLUSION

The well-defined upper eyelid vascular network pattern specifically appeared in patients with rosacea, which could be a possible clue to the diagnosis of rosacea.

Branch retinal artery occlusion with congenital common carotid artery and internal carotid artery occlusion: A case report

PURPOSE

To report a case of branch retinal artery occlusion (BRAO) of the left eye combined with left congenital common carotid artery occlusion (CCAO) and internal carotid artery occlusion (ICAO).

METHODS

Case report.

RESULTS

A 36-year-old man presented with sudden vision loss of only the left eye without any signs or symptoms of brain diseases. Fluorescein fundus angiography (FFA) showed left BRAO, and computed tomography angiography (CTA) of the head and neck showed entire left CCAO and ICAO. The patient's left vertebral artery was anastomosed with the left occipital artery via the muscular branch, supplying blood retrogradely to the left external carotid artery. The right internal carotid artery compensated for blood supply to the left anterior cerebral artery and middle cerebral artery via anterior communication, and the left posterior communication artery compensated for blood supply to the left middle cerebral artery.

CONCLUSIONS

To our knowledge, this study was the first to report a case of BRAO combined with congenital CCAO and ICAO with vision loss as the first symptom and proposed the importance of head and neck examination in retinal artery occlusion at the first visit to a doctor.

Selective elevation in external carotid artery flow during acute gravitational transition to microgravity during parabolic flight

This study sought to determine to what extent acute exposure to microgravity (0 G) and related increases in central blood volume (CBV) during parabolic flight influence the regional redistribution of intra and extra cranial cerebral blood flow (CBF). Eleven healthy participants performed during two parabolic flights campaigns aboard the Airbus A310-ZERO G aircraft. The response of select variables for each of the 15 parabolas involving exposure to both 0 G and hypergravity (1.8 G) were assessed in the seated position. Mean arterial blood pressure (MAP) and heart rate (HR) were continuously monitored and used to calculate stroke volume (SV), cardiac output ([Formula: see text]), and systemic vascular resistance (SVR). Changes in CBV were measured using an impedance monitor. Extracranial flow through the internal carotid, external carotid, and vertebral artery ([Formula: see text]ICA, [Formula: see text]ECA, and [Formula: see text]VA), and intracranial blood velocity was measured by duplex ultrasound. When compared with 1-G baseline condition, 0 G increased CBV (+375 ± 98 mL, P = 0.004) and [Formula: see text] (+16 ± 14%, P = 0.024) and decreased SVR (-7.3 ± 5 mmHg·min·L-1, P = 0.002) and MAP (-13 ± 4 mmHg, P = 0.001). [Formula: see text]ECA increased by 43 ± 46% in 0 G (P = 0.030), whereas no change was observed for CBF, [Formula: see text]ICA, or [Formula: see text]VA (P = 0.102, P = 0.637, and P = 0.095, respectively).NEW & NOTEWORTHY Our findings demonstrate that in microgravity there is a selective increase in external carotid artery blood flow whereas global and regional cerebral blood flow remained preserved. To what extent this reflects an adaptive, neuroprotective response to counter overperfusion remains to be established.

Long-term Outcomes Following Endoscopic Transnasal Surgery for Optic Neuropathy Due to Craniofacial Fibrous Dysplasia

OBJECTIVE

To investigate the feasibility of endoscopic transnasal optic canal decompression (ETOCD) guided by a navigation surgical system (NSS) for vision recovery in patients with compressive optic neuropathy (CON) caused by craniofacial fibrous dysplasia (CFD), and to explore the underlying cause of visual impairment.

METHODS

All patients underwent unilateral NSS-guided ETOCD and were followed up periodically for at least six months. Paired sample t-test and Pearson correlation analyses were used to compare continuous variables of the visual outcomes at the final review. A histopathological test of abnormal bone specimens was performed postoperatively.

RESULTS

Thirty-four patients were finally included, and all surgeries were uneventful. The best corrected visual acuity (BCVA) (logMAR units) decreased from 1.29 ± 0.80 preoperatively to 0.97 ± 0.78 at the last follow-up (p = 0.0012), improving in 28 patients (82.35%). The absolute value of mean defect (MD) significantly decreased (p < 0.001). Color vision was impaired in 17 patients preoperatively and improved in 6 patients. BCVA at the last follow-up was significantly correlated with preoperative BCVA, onset time, preoperative retinal nerve fibril layer thickness, and MD (all p < 0.05). Among 34 patients, 26 had a blunt bony process near the anterior foot of the optic chiasm. Of the total patients, 73.53% patients experienced bony fiber recurrence 6 months or earlier after surgery without visual loss.

CONCLUSION

NSS-guided ETOCD appeared to be safe and effective for visual recovery in patients with CON due to CFD, and early surgical intervention was critical for long-term recovery. Unbalanced compression of the optic canal by the blunt bony process may be a major cause of visual impairment.

LEVEL OF EVIDENCE

4 Laryngoscope, 2023.

Endoscopic endonasal surgical anatomy of the optic canal: key anatomical relationships between the optic nerve and ophthalmic artery

PURPOSE

A detailed understanding of the neurovascular relationships between the optic nerve (ON) and the ophthalmic artery (OA) in the optic canal (OC) is paramount for safe surgery. We focused on the neurovascular anatomy of this area from both an endoscopic endonasal and transcranial trajectories to compare the surgical exposures and perspectives offered by these different views and provide recommendations to increase the intraoperative safety.

METHODS

Twenty sides of ten formalin-fixed, latex-injected head specimens were utilized. The surgical anatomy and anatomical relationships of the OA in relationship to the ON along their intracranial and intracanalicular segments was studied from endoscopic endonasal and transcranial perspectives.

RESULTS

Three types of OA-ON relationships at the origin of the OA were identified: inferomedial (type 1, 35%), inferior (type 2, 55%), and inferolateral (type 3, 10%). The endoscopic endonasal trajectory offers an inferomedial perspective of the ON-OA neurovascular complex, in which the OA, especially when located inferomedially, is first encountered. When comparing with the transcranial view, all OA were covered by the nerve, type 1 was located below the medial third, type 2 below the middle third, and type 3 below the lateral third of the OC. The mean extension of the intracanalicular portion of both OA and ON was 8.9 mm, while the intracranial portion of the OA and ON were 9.3 mm and 12.4 mm, respectively. The OA, endoscopically, is located within the inferior half of the OC, and occupies 39%, 43%, and 42% of the OC height at its origin, mid, and end points, respectively. The mean distance between the superior margin of the OC at its origin and superior margin of the OA is 1.4 mm.

CONCLUSIONS

Detailed anatomical understanding of the OC, and the ON and OA at their intracranial and intracanalicular segments is paramount to safe surgery. When opening the OC dura endoscopically, our results suggest that a medial incision along the superior third of the OC with a proximal to distal direction is recommended to avoid injury of the OA.

Clinical and neuroimaging features of a familial pathogenic ACTA2 variant as a model of a vascular neurocristopathy

The clinical and neuroimaging findings of a family with a variant ACTA2 gene (c351C > G), presenting with smooth muscle dysfunction in structures of neural crest derivation, are discussed. The combination of aortic abnormalities, patent ductus arteriosus, congenital mydriasis and distinctive cerebrovascular and brain morphological abnormalities characterise this disorder. Two sisters, heterozygous for the variant, and their mother, a mosaic, are presented. Brain parenchymal changes are detailed for the first time in a non-Arg179His variant. Radiological features of the petrous canal and external carotid are highlighted. We explore the potential underlying biological and embryological mechanisms.

Embryonic Development of the Orbit

The embryonic and fetal development of the orbit comprises a series of sequential events, starting with the fertilization of the ovum and extending until birth. Most of the publications dealing with orbital morphogenesis describe the sequential development of each germinal layer, the ectoderm with its neuroectoderm derivative and the mesoderm. This approach provides a clear understanding of the mode of development of each layer but does not give the reader a general picture of the structure of the orbit within any specified time frame. In order to enhance our understanding of the developmental anatomy of the orbit, the authors have summarized the recent developments in orbital morphogenesis, a temporally precise and morphogenetically intricate process. Understanding this multidimensional process of development in prenatal life, identifying and linking signaling cascades, as well as the regulatory genes linked to existing diseases, may pave the way for advanced molecular diagnostic testing, developing minimally invasive interventions, and the use of progenitor/stem cell and even regenerative therapy.

Fetal Development of the Orbit

Human prenatal development is divided into an embryonic period and a fetal period. Intense organogenetic activity occurs in the embryonic period of prenatal life, while the fetal period is marked by less intense changes. Knowledge of the embryology of the orbit not only allows insights into how normal variations in the orbital structure arise but also provides an understanding of how congenital deformities occur when normal orbital development goes awry. In order to explore our understanding of the developmental anatomy of the orbit during the fetal period of prenatal life, the authors have summarized the major milestones in orbital morphogenesis, a temporally precise and morphogenetically intricate process. This process can be considered as an anatomic series of complex, well-orchestrated changes in morphology as well as a series of complex biochemical and molecular events that coordinate and control the anatomic development. Identifying and linking signaling pathways and regulatory genes linked with normal orbital morphogenesis is a crucial step to offer patients with chronic or incurable orbital diseases effective treatment options in the future.

Cerebral angiographic features of central retinal artery occlusion patients treated with intra-arterial thrombolysis

BACKGROUND

Central retinal artery occlusion (CRAO) is an ischemic stroke of the eye. The atherosclerotic lesions in the intracranial segment of the carotid artery (CA) and the ophthalmic artery (OphA) are not well defined. We aimed to investigate the cerebral angiographic features of CRAO patients and assess the relationship between the angiographic features and outcomes after intra-arterial thrombolysis (IAT).

METHODS

We included 101 acute non-arteritic CRAO patients treated with IAT. We analyzed the detailed angiographic features of the OphA and ipsilateral CA, visual acuity, fundus photography, and fluorescein angiography.

RESULTS

Of the 101 patients, 38 patients (37.6%) had steno-occlusive lesions in the OphA, and 62 patients (61.4%) had atherosclerotic lesions in the ipsilateral CA. The patients with a higher degree of stenosis in the OphA showed a higher degree of stenosis (P=0.049) and a more severe morphology of plaque (P=0.000) in the ipsilateral CA. Additionally, although the visual outcome was not associated with these angiographic features, the lower degree of stenosis and less severe morphology of plaque in the ipsilateral CA resulted in a significant improvement in early reperfusion rate (P=0.018 and P=0.014, respectively) and arm-to-retina circulation (P=0.016 and P=0.002, respectively) of the eye after IAT.

CONCLUSIONS

There was a significant correlation in the severity of steno-occlusive lesions between the OphA and the ipsilateral CA in patients with CRAO. The patients with less severe angiographic features in the CA showed a more improved retinal reperfusion after IAT. The angiographic findings in the CA may serve as a predictive marker for the vessel integrity of the OphA and recanalization outcome after IAT.

Role of the ophthalmic artery in the endovascular treatment for intracranial vascular diseases

The ophthalmic artery (OA) is a crucial artery. Centered at the OA, there are numerous extracranial-intracranial anastomoses. The OA and its collaterals can be involved in some intracranial vascular diseases. So, it is very important to understand its specific anatomy, variation, and role in different neurovascular diseases. The OA has various anomalies both in the origin and collateral circulation. When performing endovascular treatment (EVT), the OA may suffer unexpected embolization through the numerous dangerous anastomoses. In case of a dural arteriovenous fistula or brain arteriovenous malformation mainly fed by the OA, the OA can be the passage of EVT, during which the central retinal artery could be injured. During interventional recanalization of steno-occlusive diseases of the internal carotid artery, dissection at the cavernous segment could progress to the OA segment and occlude the origin of OA. Under the circumstance of moyamoya disease, the OA can provide collateral flow to the anterior cerebral artery. When performing EVT for OA aneurysm concurrent with moyamoya disease, the parent OA should be preserved. After placement of a flow-diverting device for ophthalmic ICA aneurysm, the covered OA could experience spontaneous occlusion, leading to visual disturbance. Hence, the OA is an extremely important artery in the EVT for intracranial vascular diseases. In this article, we would extensively review the related literature to increase our understanding of the role of OA in intracranial vascular diseases. In addition, some illustrative cases would also be provided.

A systematic review of the surgical anatomy of the orbital apex

Purpose

The orbital apex is the narrowest part of the orbit, housing the link between the intracranial cavity and orbit. Knowledge of orbital apex anatomy is crucial to selecting a surgical approach and reducing the risk of complications. Our purpose is to summarize current knowledge on surgical anatomy and attempt to reach a consensus on definition of the orbital apex.

Methods

The online databases of Embase, the Cochrane library, Web of Science and PubMed (MEDLINE) were queried in a comprehensive bibliographic search on the (surgical) anatomy of the orbital apex and consisted of a combination of two subjects, using indexed terms and free text: “Orbital Apex” and “Orbital Anatomy.”

Results

A total of 114 relevant papers were included in this review. Numerous anatomical variations are described in the literature. Variations of the optic canal include duplication (0.64%) and keyhole anomaly (2.65%). Variations in pneumatization of the anterior clinoid process were unilateral in almost 10%, bilateral in 9%, and normal in 72%. A rare variant of the superior orbital fissure (SOF) is Warwick’s foramen, which appears as if the lowest portion of the SOF was separated from the main fissure by a transverse bony bridge.

Conclusion

The definition of the orbital apex varies in the literature, and further research would most likely identify additional variations. A universal definition reporting these variations and pathology and imaging findings is essential for determining the optimal surgical approach to the orbital apex.

Electronic supplementary material

The online version of this article (10.1007/s00276-020-02573-w) contains supplementary material, which is available to authorized users.

Stapedial Artery: From Embryology to Different Possible Adult Configurations

The stapedial artery is an embryonic artery that represents the precursor of some orbital, dural, and maxillary branches. Although its embryologic development and transformations are very complex, it is mandatory to understand the numerous anatomic variations of the middle meningeal artery. Thus, in the first part of this review, we describe in detail the hyostapedial system development with its variants, referring also to some critical points of ICA, ophthalmic artery, trigeminal artery, and inferolateral trunk embryology. This basis will allow the understanding of the anatomic variants of the middle meningeal artery, which we address in the second part of the review.

Anatomic Nuances of the Ophthalmic Artery Origin from a Ventral Viewpoint: Considerations and Implications for Endoscopic Endonasal Surgery

BACKGROUND

The origin of the ophthalmic artery is within the surgical field of endoscopic endonasal approaches (EEAs) to the suprasellar and parasellar regions. However, its anatomy from the endoscopic point-of-view has not been adequately elucidated.

OBJECTIVE

To highlight the anatomy of the ophthalmic artery origin from an endoscopic endonasal perspective.

METHODS

The origin of the ophthalmic artery was studied bilaterally under endoscopic visualization, after performing transplanum/transtubercular EEAs in 17 cadaveric specimens (34 arteries). Anatomic relationships relevant to surgery were evaluated. To complement the cadaveric findings, the ophthalmic artery origin was reviewed in 200 "normal" angiographic studies.

RESULTS

On the right side, 70.6% of ophthalmic arteries emerged from the superior aspect, while 17.6% and 11.8% emerged from the superomedial and superolateral aspects of the intradural internal carotid artery, respectively. On the left, 76.5%, 17.6%, and 5.9% of ophthalmic arteries emerged from the superior, superomedial, and superolateral aspects of the internal carotid, respectively. Similar findings were observed on angiography. All ophthalmic arteries emerged at the level of the medial opticocarotid recess. Overall, 47%, 26.5%, and 26.5% of ophthalmic arteries (right and left) were inferolateral, inferior, and inferomedial to the intracranial optic nerve segment, respectively. On both sides, the intracranial length of the ophthalmic artery ranged from 1.5 to 4.5 mm (mean: 2.90 ± standard deviation of 0.74 mm).

CONCLUSION

Awareness of the endoscopic nuances of the ophthalmic artery origin is paramount to minimize the risk of sight-threatening neurovascular injury during EEAs to the suprasellar and parasellar regions.

Embryology and anatomical variations of the ophthalmic artery

PURPOSE

The ophthalmic artery (OA) has one of the most complex anatomy and the most fascinating embryological development.

METHODS

The complexity of the embryologic development of the OA resides in the implication of three different embryological systems: the carotid system, the stapedial system, and the ventral pharyngeal system.

RESULTS

This explains very well the numerous variations in origin of the OA and the importance of vascular anastomoses developed with branches of the external carotid artery and with the middle meningeal artery.

CONCLUSION

In this review, authors propose a comprehensive description of different hypotheses on the embryologic development of the OA and, in a second part, explain all anatomical variations and clinical implications of this artery.

Double Ophthalmic Arteries Arising from the Internal Carotid Artery and the Accessory Meningeal Artery: A Case Report of a New Anatomic Variation

BACKGROUND

Variant origin of the ophthalmic artery (OA) is uncommon. The majority of variant origins are from the middle meningeal artery and from the infraclinoid segment of the internal carotid artery. An OA arising from the accessory meningeal artery is an extremely rare vascular variation that has not been described previously in the English literature.

CASE DESCRIPTION

We report the first case of double origin of the OA from the supraclinoid segment of the internal carotid artery and from the accessory meningeal artery branch of the maxillary artery. A 33-year-old woman was referred to our clinic with suspicion of a middle cerebral artery aneurysm. She had nonspecific neurologic symptoms. The patient underwent cerebral magnetic resonance imaging and magnetic resonance angiography.

CONCLUSIONS

Being aware of variant origin of the OA from the accessory meningeal artery is very important for transarterial chemoembolization in the external carotid artery territory. Reconstructed images from magnetic resonance angiography are very useful to reveal the variant origin of the OA.

An Anatomic Feasibility Study for Revascularization of the Ophthalmic Artery, Part I: Intracanalicular Segment

BACKGROUND

The anatomico-functional complexity of the ophthalmic segment aneurysms is attributable to the presence of critical neurovascular structures in the surgical field. Surgical clipping of the ophthalmic artery (OpA) aneurysms can result in postoperative visual deficit due to the complexity of the aneurysm, vasospasm, or optic nerve manipulation. In this study, we aimed to characterize the feasibility of an intracanalicular OpA (iOpA) revascularization with 2 donor vessels: an intracranial-intracranial (IC-IC) bypass using the anterior temporal artery (ATA) and an extracranial-intracranial (EC-IC) bypass using the superficial temporal artery (STA). We further discuss their potential role in "unclippable" OpA aneurysms.

METHODS

Twenty cadaveric specimens were used to evaluate the operative exposure of the intradural and intracanalicular OpA segments using an extradural-intradural intracanalicular approach. The arterial caliber and length at the anastomotic sites and required donor artery lengths were measured. The feasibility of the bypass using both donors was assessed.

RESULTS

The average length of the intradural and intracanalicular segment of the OpA was 9.5 ± 1.6 mm. The mean caliber of the iOpA was 1.5 ± 0.2 mm. The mean ATA length required for an ATA-OpA anastomosis was 26.7 ± 8.9 mm, with a mean caliber of 1.0 ± 0.1 mm. The mean length of STA required for the bypass was 89.9 ± 9.7 mm, with a mean caliber of 1.92 ± 0.4 mm.

CONCLUSIONS

This study confirms the feasibility of iOpA revascularization using IC-IC and EC-IC bypasses. These techniques could potentially be used for prophylactic or therapeutic neuroprotection from retinal ischemic injury while treating complex OpA aneurysms, infiltrative tumors, or intraoperative arterial injuries.

Predictors of preoperative endovascular embolization of meningiomas: subanalysis of anatomic location and arterial supply

Introduction

Endovascular embolization of intracranial meningiomas is commonly used as an adjunct to surgical resection. We sought to describe the anatomic locations and vascular supplies of meningiomas to identify characteristics predictive of successful preoperative endovascular embolization.

Methods

We conducted a retrospective review of 139 meningioma cases receiving cerebral angiograms for possible preoperative endovascular embolization at our institution between December 2000 and March 2017. The extent of embolization, arterial supply, anatomic location, and procedural complications were recorded for each case. Univariate and multivariate analyses were performed to identify tumor characteristics that predicted successful embolization.

Results

Of the total meningioma patients undergoing preoperative angiography, 78% (108/139) were successfully embolized, with a 2.8% periprocedural complication rate (3/108). Within the subset of patients with successful embolization, 31% (33/108) achieved complete angiographic embolization. Significant multivariate predictors of embolization (either partial or complete) were convexity/parasagittal locations (OR 5.15, 95% CI 0.93 to 28.54, p=0.060), meningohypophyseal trunk (MHT, OR 4.65, 95% CI 1.63 to 13.23, p=0.004), middle meningeal artery (MMA, OR 10.89, 95% CI 3.43 to 34.64, p<0.001), and ascending pharyngeal artery supply (APA, OR 9.96, 95% CI 1.88 to 52.73, p=0.007). Significant predictors for complete embolization were convexity/parasagittal locations (OR 4.79, 95% CI 1.66 to 13.84, p=0.004) and embolized APA supply (OR 6.94, 95% CI 1.90 to 25.39, p=0.003). Multiple arterial supply was a negative predictor of complete embolization (OR 0.38, 95% CI 0.15 to 0.98, p=0.05).

Conclusions

Tumor characteristics can be used to predict the likelihood of preoperative meningioma embolization. Parasagittal and convexity meningiomas, and those with APA supply, are most likely to achieve complete angiographic embolization.

Usefulness of External Carotid Artery Angiogram with Manual Carotid Compression in Ophthalmic Artery Aneurysm

Objective

Identifying collaterals from external carotid artery (ECA) is necessary before treatment of ophthalmic artery (OphA) aneurysm. We present a manual carotid compression test to verify collaterals in ophthalmic artery aneurysms, and evaluate its usefulness.

Materials and Methods

From March 2013 to December 2017, endovascular coiling was performed 19 consecutive patients with 20 OphA aneurysms. We performed manual carotid compression test for patients who had aneurysms incorporating entry of OphA. Clinical and angiographic outcomes were investigated.

Results

Of 13 cases underwent manual carotid compression test, 12 cases were confirmed collateral flow from ECA to OphA. During the coil embolization, we tried to maintain the original OphA flow even if it has a collateral anastomosis. Among them, OphA occlusion occurred in one patient during coiling. Recurrence of aneurysm was occurred in a ruptured case and additional embolization was required.

Conclusions

The manual carotid compression test is useful method to identify the collaterals from ECA in patients with OphA aneurysm. This test can be used as a screening test for confirming collateral flow in OphA aneurysms or as an alternative for patients who are difficult to perform BTO.

Embryologic and Fetal Development of the Human Orbit

PURPOSE

To review the recent data about orbital development and sort out the controversies from the very early stages during embryonic life till final maturation of the orbit late in fetal life, and to appreciate the morphogenesis of all the definitive structures in the orbit in a methodical and timely fashion.

METHODS

The authors extensively review major studies detailing every aspect of human embryologic and fetal orbital morphogenesis including the development of extraocular muscles, orbital fat, vessels, nerves, and the supportive connective tissue framework as well as bone. These interdisciplinary studies span almost a century and a half, and include some significant controversial opposing points of view which the authors hopefully sort out. The authors also highlight a few of the most noteworthy molecular biologic studies regarding the multiple and interacting signaling pathways involved in regulating normal orbital morphogenesis.

RESULTS

Orbital morphogenesis involves a successive series of subtle yet tightly regulated morphogenetic events that could only be explained through the chronological narrative used by the authors. The processes that trigger and contribute to the formation of the orbits are complex and seem to be intricately regulated by multifaceted interactions and bidirectional cross-talk between a multitude of cellular building raw materials including the developing optic vesicles, neuroectoderm, cranial neural crest cells and mesoderm.

CONCLUSIONS

Development of the orbit is a collective enterprise necessitating interactions between, as well as contributions from different cell populations both within and beyond the realm of the orbit. A basic understanding of the processes underlying orbital ontogenesis is a crucial first step toward establishing a genetic basis or an embryologic link with orbital disease.

Review of the main surgical and angiographic-oriented classifications of the course of the internal carotid artery through a novel interactive 3D model

The course of the internal carotid artery (ICA) and its segment classifications were reviewed by means of a new and freely available 3D interactive model of the artery and the skull base, based on human neuroimages, that can be freely downloaded at the Public Repository of the University of Barcelona (http://diposit.ub.edu/dspace/handle/2445/112442) and runs under Acrobat Reader in Mac and Windows computers and Windows 10 tablets. The 3D-PDF allows zoom, rotation, selective visualization of structures, and a predefined sequence view. Illustrative images of the different classifications were obtained. Fischer (Zentralbl Neurochir 3:300-313, 1938) described five segments in the opposite direction to the blood flow. Gibo-Rothon (J Neurosurg 55:560-574, 1981) follow the blood flow, incorporated the cervical and petrous portions, and divided the subarachnoid course-supraclinoid-in ophthalmic, communicating, and choroidal segments, enhancing transcranial microscopic approaches. Bouthillier (Neurosurgery 38:425-433, 1996) divided the petrous portion describing the lacerum segment (exposed in transfacial procedures and exploration of Meckel's cave) and added the clinoid segment between the proximal and distal dural rings, of interest in cavernous sinus surgery. The Kassam's group (2014), with an endoscopic endonasal perspective, introduces the "paraclival segment," including the "lacerum segment" and part of the intracavernous ICA, and details surgical landmarks to minimize the risk of injury. Other classifications are also analyzed. This review through an interactive 3D tool provides virtual views of the ICA and becomes an innovative perspective to the segment classifications and neuroanatomy of the ICA and surrounding structures.

Functional Vascular Anatomy of the Brain

Functional vascular anatomy is the study of anatomy in its relation to the function that figures out the normal and pathological vascularization of the brain and spinal cord. The mechanism of anatomical variations (e.g. fenestration of the basilar artery, persistent primitive trigeminal artery, and aberrant subclavian artery) can be explained according to the embryological development of the cardiovascular system. The most developmental process is common among the species of the vertebrates from the fish to the mammalian in the early phase of embryo. Thus, it is possible to deduce the reasons of vascular variants in terms of phylogeny. Such an embryological parallelism like the comparative anatomy provides the new insights into the nature of our vascular system. In addition, learning more about the hemodynamic consequence may help to realize the underlying physiopathology of cerebral arterial remodeling and stroke in patients with these vascular variants. This perception may facilitate better understanding of the vascular pathologies and lead to the appropriate decision making not only in the diagnostic work, but also in the interventional procedures. The aim of this study is to introduce the meanings of functional anatomy in the clinical application of vascular diseases and anomalous of the central nervous system.

Endoscopic endonasal anatomy of the ophthalmic artery in the optic canal

BACKGROUND

The endoscopic endonasal opening of the optic canal has been recently proposed for tumors with medial invasion of this canal, such as tuberculum sellae meningiomas. Injury of the ophthalmic artery represents a dramatic risk during this maneuver. Therefore, the aim of this study was to analyze the endoscopic endonasal anatomy of the precanalicular and canalicular portion of this vessel, discussing its clinical implication.

METHODS

The course of the ophthalmic artery was analyzed through five endoscopic endonasal dissections, and 40 nonpathological consecutive MRAs were reviewed.

RESULTS

The ophthalmic artery arises from the intradural portion of the supraclinoid internal carotid artery, in 93 % of cases about 1.9 mm (range: 1-3) posterior to the falciform ligament. At the entrance into the optic canal, the ophthalmic artery is located infero-medially to the optic nerve in 13 % of cases. In 50 % of these cases the artery moves infero-laterally along its course, remaining in a medial position in the others. In cases with an non medial entrance of the ophthalmic artery, it runs infero-lateral to the optic nerve for its entire canalicular portion, with just one exception.

CONCLUSION

The endoscopic endonasal approach gives a direct, extensive and panoramic view of the course of the precanalicular and canalicular portion of the ophthalmic artery. Dedicated high-field neuroimaging studies are of paramount importance in preoperative planning to evaluate the anatomy of the ophthalmic artery, reducing the risk of jeopardizing the vessel, particularly for those uncommon cases with an infero-medial course of the artery.

Ophthalmic artery originating from the anterior cerebral artery: anatomo-radiological study, histological analysis, and literature review

The ophthalmic artery has an anomalous origin in 2-3 % of cases and rarely arises from the anterior cerebral artery. Herein, we provide the first anatomical, radiological, and histological description of such an anomalous origin, together with a literature review. During the anatomical dissection of an 81-year-old Caucasian male, the absence of the right ophthalmic artery in its usual location was evident from an endonasal transsphenoidal perspective. The specimen was then studied in detail, through multiple dissections, corrosion casting, high-resolution CT, and histological analysis. The English literature on anomalous origins of the ophthalmic artery was reviewed, together with reported associated pathologies. Anatomo-radiological analysis documented that the right ophthalmic artery arose from the inferior surface of A1 tract of the anterior cerebral artery (A1) and passed over the optic nerve in its subarachnoid tract. A meningo-ophthalmic artery was evident on the same side and reached the orbit through the superior orbital fissure. Histological examination of both internal carotid artery (ICA) walls documented a significantly decreased thickness of the tunica media and adventitia on the side of the anomalous ophthalmic artery, with a significantly different content of collagen types I and III. The literature review documented an association of aneurysms and anomalous ophthalmic arteries. To the best of our knowledge, this is the first anatomical report that includes a radiological and arterial wall analysis of a persistent ventral ophthalmic artery. The latter provides histological data that support the clinical evidence of a higher association of aneurysms with anomalous origins of the ophthalmic artery.

Anatomy of the Ophthalmic Artery: A Review concerning Its Modern Surgical and Clinical Applications

Anatomy of ophthalmic artery has been thoroughly studied and reviewed in many anatomical and surgical textbooks and papers. Issues of interest are its intracranial and extracranial course, its branches, its importance for vision, and its interaction with various intracranial pathologies. Improvement of our understanding about pathophysiology of certain diseases like aneurysm formation, central retinal artery occlusion, and retinoblastoma and also invention of new therapeutic modalities like superselective catheterization, intra-arterial fibrinolysis, and intra-arterial chemotherapy necessitate a reappraisal of its anatomy from a clinical point of view. The aim of this review is to examine clinical anatomy of ophthalmic artery and correlate it with new diagnostic and therapeutic applications.